When installing your email signature into the Outlook App for iOS, you will need to use the HTML source code of the email signature, rather than copying the signature itself.
Open the Outlook App on your iPhone/iPad. Tap the menu button from the top left.
Tap the settings gear icon on the bottom left of the menu.
When you’re in the settings menu, tap on the signature section.
Press and hold over the email signature area, paste the HTML source code of your new signature.
Your email signature is now installed!